Executing a JCT Building Contract: Step-by-Step Guide for Homeowners

Introduction

The building contract is the foundation document of your relationship with your contractor. It sets out the agreed scope of works, the contract sum, the programme, the payment terms, and the rights and obligations of both parties if things go wrong. For residential extension and renovation projects in north London, the JCT Minor Works Building Contract (for straightforward projects up to approximately £250,000) or the JCT Intermediate Building Contract (for more complex projects) are the standard forms used. This guide explains the steps involved in executing a building contract and the key provisions you should understand before signing.

Why a Written Building Contract Is Essential

Many residential building projects proceed without a proper written contract — on a "gentlemen's agreement" basis with a brief letter or email exchange confirming the price. This approach exposes the homeowner to significant risk:

• No defined scope of works — the contractor and homeowner may have different understandings of what is included
• No defined payment mechanism — disputes about when and how much to pay cannot be resolved by reference to a contract
• No retention mechanism — no withholding against defects during the Defects Liability Period
• No Practical Completion Certificate — no defined point at which risk transfers from contractor to employer
• No formal dispute resolution process — disagreements must be resolved by litigation rather than adjudication

A properly executed JCT contract provides all these protections. The cost of obtaining one (the form is purchased from the RIBA Bookshop for approximately £40–£80) is trivial relative to the protection it provides.

Choosing the Right JCT Form

The main JCT forms used for residential work are:

• JCT Minor Works Building Contract (MW): Appropriate for simple, straightforward projects where the employer supplies design information to the contractor. Suitable for most residential extensions up to approximately £250,000–£300,000.
• JCT Intermediate Building Contract (IC): More comprehensive, with additional mechanisms for nominated subcontractors, performance bonds and more complex payment and certification provisions. Appropriate for projects of greater scale or complexity.
• JCT Homeowner Contracts (HO/C and HO/B): Simplified forms specifically designed for domestic clients who may not have professional representation. Suitable for straightforward, smaller projects.

Your architect will recommend the appropriate form for your project.

The Contract Particulars

The JCT Minor Works contract comprises standard conditions (which should not be amended without legal advice) and the Contract Particulars — a schedule that fills in the project-specific details. Key Contract Particulars include:

• The Employer and Contractor: Full legal names and addresses of both parties
• The Contract Administrator: The named person (typically the architect) who will administer the contract
• Description of the Works: A brief description of the project that identifies the scope
• The Contract Documents: The list of drawings, specification and schedules that form the contract — every drawing and document that defines what the contractor is to build must be listed
• The Date for Completion: The contractual completion date — the date by which the contractor is required to achieve practical completion
• Liquidated Damages: The rate of damages (per week) if the contractor fails to complete by the completion date — or "Nil" if not applicable
• Retention Percentage: Typically 5% (or 3% for smaller projects)
• Defects Liability Period: Typically 12 months from practical completion
• Payment Period: The number of days from the assessment date within which payment must be made (typically 14 days)
• Contract Sum: The agreed price for the works

Checking the Contract Before Signing

Before signing the contract, both parties should confirm:

• The contract sum matches the agreed tender price after clarifications
• All relevant drawings and specification documents are listed in the Contract Documents schedule
• The Date for Completion is realistic relative to the agreed programme
• The contractor has confirmed adequate insurance cover (public liability, employer's liability, contractor's all risks)
• The health and safety information required under CDM has been prepared
• The contractor has read and accepted the specification in full

Executing the Contract

A JCT building contract is executed as a simple contract (signed by both parties) or as a deed (requiring witnessed signature and a longer limitation period of 12 years rather than 6 years). For residential projects of significant value — above approximately £100,000 — execution as a deed is recommended. The contract is signed in two identical counterparts — one kept by the employer, one by the contractor.

After Execution

Once the contract is executed:

• The architect issues the contractor with all contract documents including the full drawing set and specification
• The contractor provides their insurance certificates and CDM documentation
• A Start on Site meeting is held to confirm programme, site access, working hours and health and safety arrangements
• The contractor mobilises and construction begins

Conclusion

Executing a JCT building contract correctly — with all contract particulars completed, all contract documents listed, and all pre-conditions satisfied — creates the contractual framework that manages your construction project professionally. It protects both the homeowner and the contractor by providing clear rules for payment, completion, defects and disputes. An architect managing the contract execution will ensure the form is correctly completed, the contract documents are complete, and the contract is signed before work begins — not as a formality, but as the contractual foundation of a professionally managed project.